Reputable Christian scholars are outright rejecting one author's message that the Bible gives mixed and contradictory teachings on sex and sexuality.

Earlier this week, a Newsweek article entitled, "What the Bible Really Says About Sex," brought attention to the work of Jennifer Wright Knust, author of Unprotected Texts: The Bible’s Surprising Contradictions About Sex and Desire.

Knust, a religion professor at Boston University, argues that there are cases in the Bible where premarital sex, homosexuality and prostitution is permissible, according to her book and the Newsweek piece.

Evangelical scholars say she fails to demonstrate authentic scholarship and correct biblical interpretation despite teaching religion and being an ordained American Baptist pastor.

"Jennifer Knuts offers a revisionist interpretation of the biblical texts. Her interpretation departs, not only from the traditional ways those texts are interpreted, but also from the true meaning of what the texts actually say," Dr. Claude Mariottini, professor of Old Testament at Northern Baptist Seminary, told The Christian Post.

In his blog post responding to the Newsweek piece, Dr. Albert Mohler, president of The Southern Baptist Theological Seminary, said the Bible already presents a "clear and consistent sexual ethic" and that the issue at hand is not lack of clarity.

"The real problem here is not that the Bible is misunderstood and in need of revision," he wrote Wednesday. "To the contrary, the real problem is that the ethic revealed in the Bible is both rejected and reviled."

In an interview posted Thursday on the Huffington Post, Knust contended to Stephen Prothero, author of Religious Literacy, that the story of Ruth is an example of how premarital sex is "a source of God's blessing" in the Bible. She claimed that the Bible's record of Ruth "uncovering the feet" of Boaz and lying down at his feet is actually a scene of the great grandparents of King David having sex. "Feet" can be a euphemism for male genitals, according to Knust.

Dr. Paul Copan, a philosophy professor at Palm Beach Atlantic University in West Palm Beach, Fla., told The Christian Post that he believes Ruth's uncovering of Boaz's feet was just that and that nothing sexual took place.

"The Bible doesn't shy away from recording sexual encounters and would have recorded it if one took place," he said.

President of the Evangelical Philosophical Society, Copan also pointed out that the grammar in the Bible doesn’t support a sexual act. The word "lie" can be used in a sexual way, such as Potiphar's wife telling Joseph "lie with me," he noted. But in the story of Ruth, "the word is used here without sexual connotations," said Copan.

Mariottini acknowledged that "feet" can refer to "genitals" in a few passages of the Old Testament, but to say that "Ruth exposed Boaz’s genitals, is to read a sexual meaning into the text that may or may not be there," he said.

"Even if Ruth exposed Boaz’s genitals, it does not mean that they had sexual intercourse. It is possible that Ruth was tricking Boaz into thinking they had sex," offered the Old Testament professor.

Bottom line: "The case of Ruth cannot be used to give approval to premarital sex," said Mariottini.

Both Copan and Mariottini referred to Deuteronomy 22:28-29 to explain that the Bible is against premarital sex. According to the passage, sex consummates the marriage so if a man has violated a virgin woman, he must pay her father 50 pieces of silver and also take her as his wife, the scholars said.

They also cited the passage in Genesis 2:24, which states, "This is why a man leaves his father and mother and bonds with his wife, and they become one flesh."

Scripture affirms God's creation order of marriage between a man and a woman and sexual pleasure as taking place in the context of marriage, they said.

In another controversial claim, Knust also argues that the Bible justifies prostitution, pointing to the story of Tamar.

Tamar was left a widow after the Lord punished Er, Judah's eldest son, with death for his wickedness. Judah then asks his second eldest son, Onan, to marry Tamar and give her an offspring but he, too, is slain by the Lord after he intentionally withheld his seed from Tamar. When the third son Shelah was grown but was given to wed Tamar, she posed as a prostitute and had sex with her father-in-law.

"The Bible does not approve prostitution, but like in our society today, prostitution was very common," said Mariottini.

"The reason Tamar dressed like a prostitute was because Judah violated a societal rule and refused to provide an heir for his dead son. So, she was forcing him to fulfill his obligation," he said.

In a commentary to CNN this week, Knust takes another stab at the Bible's claims on sexuality by arguing that Scripture supports homosexuality. Again using Old Testament characters to make her point, she sets her sights on David and Jonathan, alleging that the two were same-sex partners.

"There is no evidence that David and Jonathan were gay partners," stated Mariottini. "Both of them were married and had children. They were just friends who had the kind of friendship that was common in the Ancient Near East. This type of friendship is unknown today. This is the reason people mistake this kind of friendship with a gay relationship."

Mohler had this to say about Knust's claim on homosexuality, "No Jewish or Christian interpreter of the Bible had ever suggested that the relationship between David and Jonathan was homosexual – at least not until recent decades."

"The revisionist case is equally ludicrous across the board. We are only now able to understand what Paul was talking about in Romans 1? The church was wrong for two millennia?" he asked rhetorically.

Knust acknowledged in her CNN commentary that same-sex intimacy is condemned in a "few" biblical passages, but claims that "these passages, which I can count on one hand, are addressed to specific sex acts and specific persons, not to all humanity forever, and they can be interpreted in any number of ways."

Not so, according to Copan.

Copan, who addresses the topics of homosexuality and gay marriage in his book When God Goes to Starbucks, said that homosexuality is strictly prohibited by the Bible in Leviticus 18:22 and again by Apostle Paul in 1 Corinthians 6.

Homosexuality "goes against the very design that God intended: marriage is between husband and wife," said Copan, reaffirming the passage in Genesis.

"Paul speaks very strongly against homosexuality," he said. "He says that these sorts of things are not to be approved in the Kingdom of God. He is also saying that people can be redeemed from this."

In his book, Copan cited the work of Richard Hays, dean of Duke Divinity School, who calls such attempts to label Ruth and Naomi as lesbians or David and Jonathan as gays "exegetical curiosities” that just aren’t taken seriously by biblical scholars.

"The Scriptures offer no indications – no stories, no metaphors – that homosexual relationships are acceptable before God," concluded Copan in When God Goes to Starbucks.